Use of polymer compositions for coating surfaces, and surface coatings comprising such compositions

ABSTRACT

The invention describes the use of compositions containing at least one thermoplastic polymer and an epoxy resin modified by at least one aromatic polyamine to coat surfaces, especially pipes through which oil is transported. The polymer compositions used contain at least one thermoplastic polymer which is preferably amorphous selected from the group formed by polysulphones, polyetherimides and polyphenylene esters and at least one epoxy resin modified by at least one aromatic polyamine containing at least two primary amine groups in its molecule. Different layers of polymers are deposited on different types of surface, more particularly as internal and external coatings for conduits. The invention also provides a surface coating comprising such compositions. Multi-layer coatings are also produced.

[0001] During the course of a study on surface coatings, the Applicantwas concerned with polymer compositions. Following this work,compositions of particular interest for surface coatings were developed,these compositions containing at least one thermoplastic polymer whichis usually amorphous or of low crystallinity, and at least one epoxyresin modified by at least one aromatic polyamine.

[0002] The present invention concerns the use of these compositions tocoat metal or other surfaces, for example for receptacles or conduits.These compositions are particular suitable for protecting surfaces, inparticular metal surfaces. These compositions are used to coat conduitsand pipelines in particular, especially metal conduits and steelpipelines.

[0003] Pipelines are metal tubes, often formed from steel, essentiallyused in wells to transport crude oil and natural gas, but any type offluid could be transported by such pipelines. The internal surface ofthe pipeline is corroded by the transported fluid. When the transportedfluid is oil, the sulphur-containing compounds contained in the oil arethe main causes of the corrosion. When drilling offshore, the externalsurface of the pipeline is also corroded by sea water.

[0004] The principal problem with depositing a polymer on a metalsurface, for example the external and/or internal surface of a pipeline,for example of steel, is the behaviour of the polymer when it issubjected to heat stress. Even if the oil is cooled before transportingit, the pipeline is often heated to a temperature of about 50° C. to200° C. by contact with hot oil. Certain polymers, for examplepolypropylene, tend to distort and no longer adhere to the metal oncethe temperature exceeds 130° C. Other polymers, such as polyetherimidesor polysulphones, adhere at high temperatures but their applicationtemperature (at which it is deposited on the metal) is higher, about360° C. Further, metals, in particular steel—frequently used in theproduction of pipelines—, may undergo phase distortions from atemperature of about 250° C., and certain of their mechanical andphysical properties can be altered.

[0005] In addition, good adhesion of the polymer at a higher temperatureenables the oil to be transported without the need to cool it, or atleast it only needs to be cooled to a lesser extent. At a relativelyhigh temperature, oil is less viscous and therefore easier to transport.

[0006] The use of the polymer compositions of the present inventionovercomes the above disadvantages; in particular, such use producespipelines with a coating with good adhesion, good stiffness, and goodresistance to sea water. Further, the properties of the polymercompositions used are only slightly altered when these compositions areaged.

[0007] The polymer compositions used contain at least one thermoplasticpolymer, usually having a high glass transition temperature andpreferably being amorphous or of low crystallinity, usually selectedfrom the group formed by polysulphones, polyetherimides andpolyphenylene ethers and at least one epoxy resin modified by at leastone aromatic polyamine containing at least two primary amine groups inits molecule; preferably, sterically hindered polyamines are selected,i.e., they contain at least one alkyl substituent containing 1 to 12carbon atoms located alpha to one of the amine groups. In the remainderof the description, the polyamines described above are termed “aromaticpolyamines”.

[0008] Preferably, the polymer compositions used contain at least onethermoplastic polymer in an amount of about 15% to 98% by weight, morepreferably 30% to 70% by weight, with respect to the total compositionweight, and at least one epoxy resin modified by at least one aromaticpolyamine in an amount of about 2% to 85% by weight, preferably about30% to 70% by weight, with respect to the total composition weight.

[0009] The term “polysulphone” may be the source of an ambiguity. Thefirst polymer of commercial importance with a base unit containing asulphone group —SO₂— was, the polymer sold by AMOCO under the trade nameUDEL. Because of this, this particular polysulphone is often designatedby the generic term polysulphone. In the present description, the term“polysulphone” is used in its generic sense, and not just the limitingsense of a UDEL type polysulphone.

[0010] The polysulphones used in the polymer compositions of theinvention are preferably aromatic polysulphones, more preferably UDELtype polysulphones, RADEL A polysulphone type polyether-sulphones soldby AMOCO, and RADEL R polysulphone type polyphenylene sulphones alsosold by AMOCO.

[0011] The polyetherimides used in the polymer compositions arepreferably ULTEM type polyetherimides sold by General Electric Plastics.

[0012] The polyphenylene ethers used in the polymer compositions arepreferably PPE 800 type polyphenylene ethers sold by General ElectricPlastics.

[0013] As used in the present invention, the thermoplastic polymers canbe used alone, mixed with each other or mixed with other polymers suchas aromatic polyetherketones or polyphenylene sulphides. Polymercompositions comprising aromatic polyetherketones contain about 1% to50% by weight thereof with respect to the total weight of thermoplasticpolymers. Polymer compositions comprising polyphenylene sulphidescontain about 1% to 50% by weight thereof with respect to the totalweight of thermoplastic polymers.

[0014] The epoxy resins modified by at least one aromatic polyamine,preferably sterically hindered, used in the polymer compositions areepoxy resins formed from at least one polyepoxide containing at leasttwo epoxy groups in its molecule and at least one aromatic polyaminecontaining at least two primary amine groups in its molecule, and atleast one alkyl substituent containing 1 to 12 carbon atoms locatedalpha to one of the amine groups, the mole ratio of the amine to theepoxy being such that each amine group corresponds to 1.6 to 2.6 epoxygroups.

[0015] The aromatic polyamines are selected for their low reactivity andfor their non toxic nature.

[0016] The epoxy resin can be selected from the group formed by thefollowing commercially available resins: the diglycidylether ofbis-phenol-A or bis-phenol F, bis-phenol formol resin, phenol-novolacresin, cycloaliphatic resins, tri- or tetrafunctional resins, resinsformed from triglycidylether-isocyanurate and/ortriglycidylether-cyanurate and/or triglycidyl-cyanurate and/ortriglycidyl-isocyanurate or mixtures of at least two of these resins.

[0017] The epoxy resins obtained from the epoxy resins cited in U.S.Pat. No. 4,921,047 can also be used in the present invention.

[0018] The aromatic polyamines used in the polymer compositions includea first series of aromatic amines comprising a single aromatic ring suchas 3,5-diethyl-2,4-dinitrotoluene, 3,5-diethyl-2,6-diaminotoluene andmixtures of these two isomers. Usually, a mixture of these two isomersgenerally known as DETDA is used.

[0019] In a second series of amines used, amines containing at least twoaromatic rings can be considered, these two aromatic rings generallybeing connected to each other by a bivalent linear or branchedhydrocarbon residue containing 1 to 18 carbon atoms. These two aromaticrings are either connected via a bivalent alkyl group or are connectedone to the other via a bivalent linear or branched hydrocarbon residuecontaining 6 to 18 carbon atoms and containing an aromatic ring.

[0020] The amine can also contain at least one substituent selected fromthe group formed be fluorine, iodine, bromine and chlorine. Itpreferably contains at least two alkyl substituents, each being alphaeither side of an amino group.

[0021] When the two aromatic rings are connected via a bivalent alkylresidue, this residue is preferably a methylidene group which is nonsubstituted or substituted by at least one radical selected from alkylradicals and halogenoalkyl radicals containing 1 to 3 carbon atoms. Asan example, this alkyl residue is selected from the group formed by themethylidene group, the isopropylidene group, the halogenoisopropylidenegroups, and the hexafluoroisopropylidene group. In this case, the amineis preferably selected from the group formed by:

[0022] 4,4′-methylene-bis(2,6-dimethylaniline) or M-DMA;

[0023] 4,4′-methylene-bis(2-isopropyl-6-methyl-aniline) or M-MIPA;

[0024] 4,4′-methylene-bis(2,6-diethylaniline) or M-DEA;

[0025] 4,4′-methylene-bis(2,6-diisopropylaniline) or M-DIPA; and

[0026] 4,4′-methylene-bis(3-chloro-2,6-diethylaniline) or M-CDEA.

[0027] Of these amines, 4,4′-methylene-bis(2,6-diethylaniline) and4,4′-methylene-bis(3-chloro-2,6-diethylaniline) are of particularinterest.

[0028] When the amine contains two aromatic rings which are connected toeach other via a bivalent hydrocarbon residue which may or may not besubstituted, containing 6 to 18 carbon atoms and containing an aromaticring, it is preferably selected from the group formed by:

[0029] 4,4′-(phenylene-diisopropyl)-bis(2,6-dimethyl-aniline);

[0030] 4,4′-(phenylene-diisopropyl)-bis(2,6-diethyl-aniline);

[0031] 4,4′-(phenylene-diisopropyl)-bis(2,6-dipropyl-aniline);

[0032] 4,4′-(phenylene-diisopropyl)-bis(2,6-diisopropyl-aniline);

[0033] 4,4′-(phenylene-diisopropyl)-bis(2,6-dimethyl-3-chloro-aniline);

[0034] 4,4′-(phenylene-diisopropyl)-bis(2,6-diethyl-3-chloro-aniline);

[0035] 4,4′-(phenylene-diisopropyl)-bis(2,6-dipropyl-3-chloro-aniline);

[0036]4,4′-(phenylene-diisopropyl)-bis(2,6-diisopropyl-3-chloro-aniline);

[0037] 3,3′-(phenylene-diisopropyl)-bis(2,6-dimethyl-aniline);

[0038] 3,3′-(phenylene-diisopropyl)-bis(2,6-diethyl-aniline);

[0039] 3,3′-(phenylene-diisopropyl)-bis(2,6-dipropyl-aniline);

[0040] 3,3′-(phenylene-diisopropyl)-bis(2,6-dimethyl-3-chloro-aniline);

[0041] 3,3′-(phenylene-diisopropyl)-bis(2,6-diethyl-3-chloro-aniline);

[0042] 3,3′-(phenylene-diisopropyl)-bis(2,6-dipropyl-3-chloro-aniline);

[0043] 3,3′-(phenylene-diisopropyl)-bis(2,6-diisopropyl-aniline); and

[0044]3,3′-(phenylene-diisopropyl)-bis(2,6-diisopropyl-3-chloro-aniline).

[0045] The polymer compositions of the present invention can alsocontain catalysts which are active for the reaction between the epoxyresins and the sterically hindered aromatic polyamines. The mostfrequently used active catalysts are imidazoles, tertiary amines andboron trifluoride based complexes. Additives selected from the groupformed by antioxidants, pigments, adhesion promoters, heat stabilisersand organic, mineral or metallic fillers can also be added.

[0046] These polymer compositions are preferably prepared without asolvent in the molten state at a temperature of about 100° C. to 250°C., preferably about 150° C. to 200° C. This preparation is preferablycarried out using a mixer such as a twin screw extruder. In thispreferred mode of preparation, the epoxy resins, aromatic polyamines andany additives are introduced into the mixer in the form of a premix towhich the thermoplastic polymer is added; each reactant can also beseparately introduced into the mixer via different inlet zones or via asingle inlet zone. It is also possible to mix the thermoplastic polymersand epoxy resins first, then to acid the aromatic polyamine. It is alsopossible to introduce the aromatic polyamine into the mixer into a zoneclose to the zone for recovering the polymer composition.

[0047] Once the mixture has been produced, the polymer composition isformed then preferably cured. Curing generally consists of heating thecomposition to a temperature of about 200° C. to 250° C., for example,for a period of about 10 minutes to 12 hours. It is preferably carriedout in an oven.

[0048] Layers of polymer compositions can thus be deposited on differenttypes of conduits, in particular on pipelines produced from metal, moreparticularly from steel. Internal and external coatings can be formed.Different application methods have been studied. Of the possibleapplication methods, dusting and extrusion deposition methods arepreferred. The thickness of the polymer composition layers formed isgenerally about 10×10⁻⁶ m (10 micrometers) to 1×10⁻² m (1 centimeter),preferably about 50×10⁻⁶ m (50 micrometers) to 5×10⁻³ m (5 millimeters).

[0049] Uses for polymer compositions for coating surfaces withmulti-layers have also been tested. Up to 5 superimposed layers havebeen produced. Preferably, 2 to 4 layers were superimposed in the tests.

[0050] Thus one polymer composition layer containing at least onethermoplastic polymer and at least one epoxy resin modified by at leastone polyamine was deposited on the metal, in particular on steel or onsteel coated with an anti-corrosion primer and/or an adhesion promoter.Deposits on other materials, in particular on other polymers, were alsostudied.

[0051] Uses for polymer compositions for coating surfaces withmulti-layers were also tested. Thus one (or more) layers of polymercomposition containing at least one thermoplastic polymer and at leastone epoxy resin modified by at least one polyamine had deposited on it alayer of a polymer composition containing at least one thermoplasticpolymer and at least one epoxy resin modified by at least one aromaticpolyamine, the layers containing identical or different thermoplasticpolymers in identical or different proportions.

[0052] A layer of a polymer composition containing at least onethermoplastic polymer and at least one epoxy resin modified by at leastone aromatic polyamine has also had deposited on it reactive polymerswith good adhesion to the layers onto which they are deposited, such aspolymers with one or more reactive functions for example epoxy, alcohol,amine, acid, anhydride, thiol or polyolefins with functions which reactwith epoxy or polar functions, or a modified polyolefin P1 containing atleast one succimide ring substituted on the nitrogen by a reactivegroup, said ring being supported either by the main chain or by the sidechain. It is also possible to use the product resulting from thereaction of this modified polyolefin with at least one polyepoxidecontaining at least two epoxy groups in its molecule.

[0053] This polyolefin P1 can be defined as being the product resultingfrom the reaction of at least one polyolefin with at least one compoundcontaining a maleimide ring substituted on the nitrogen by a reactivegroup with formula —R— (X)_(n) where X represents a reactive group, nrepresents a number equal to 1 or more and R is a residue containing atleast one carbon atom. Usually, n equals 1 and in this case the compoundcontaining a maleimide ring used in the present invention is representedby the formula (I) below:

[0054] The reactive group -X is normally selected from a hydroxyl group,a carboxyl group, a carboxamide group, a carboxylic acid halide group, athiol group, a thio-carboxyl group, an amine group, a halogen, an epoxygroup and an esterified carboxyl group where the ester portion comprisesa reactive group. When a plurality of groups -X are present, they can beidentical or different.

[0055] The reactive group -X is usually selected from groups which canreact with epoxy functions by oxirane ring opening. Usually, compoundscontaining a reactive group selected from the carboxyl group, thecarboxamide group, an acid halide group, for example a carboxylic acidhalide group, are used. The carboxyl group is preferred.

[0056] The group —R— is normally selected from saturated or unsaturated,substituted or non substituted aliphatic hydrocarbon groups, andsubstituted or non substituted aromatic groups. Generally, nonsubstituted groups are preferred and usually the groups contain at leastone aromatic ring. An example of a group which is often used is abenzene group ortho, meta or para to the nitrogen atom and to a reactivegroup -X. Usually, the para or meta form is used.

[0057] The polyolefins used to form this layer can be any polyolefinwhich is well known to the skilled person. Preferably, polyolefmsobtained from at least one unsaturated monomer containing one or moreunsaturated bonds is used, usually selected from the group formed byethylene, propene, butenes and norbornenes. Thus these polyolefins canbe formed by homopolymerisation or copolymerisation of at least twomonomers.

[0058] These layers of polymer compositions with one or more reactivefunctions as defined( above are generally about 1×10⁻⁶ m (1 micrometer)to 500×10⁻⁶ m (500 micrometers) thick, preferably about 100×10⁻⁶ m (100micrometers) to 400×10⁻⁶ m (400 micrometers) thick.

[0059] A preferred use for the polymer compositions containing at leastone thermoplastic polymer and at least one epoxy resin modified by atleast one aromatic polyamine for coating the external surfaces ofconduits consists of forming the following multi-layer. At least onefirst layer containing at least one thermoplastic polymer and at leastone epoxy resin modified by at least one aromatic polyamine is directlydeposited on the conduit—or onto the conduit after depositing, ananti-corrosion primer and/or an adhesion promoter. On this layer, asecond layer of the polymer defined above is deposited, having one ormore reactive ianctions and with good adhesion to the first layer.Finally, this system has deposited on it a layer of commerciallyavailable polymer selected from the group for med by polyolefins, suchas polyethylenes and polypropylenes, and with good compatibility withthe second layer: as an example, a layer of commercially availablepolyethylene will be deposited on a layer of modified polyethylene—withat least one reactive function.

[0060] This last layer can be in the form of a solid or it can becellular. Further, it is generally about 10⁻³ m (1 millimetre) to about10×10⁻² m (10 centimetres) thick.

[0061] More generally, at least one polymer composition containing atleast one thermoplastic polymer and at least one epoxy resin modified byat least one aromatic polyamine can be used as an intermediate layerbetween a surface and a layer of a thermoplastic polymer compositioncontaining at least two distinct polymers at least one of which is apolymer comprising at least one reactive function, and at least onemodified polyolefin containing at least one succimide ring substitutedon the nitrogen by a reactive group, said ring being supported either bythe main chain or by the side chain.

[0062] Of the methods for depositing these multi-layer coatings, onepreferred method consists of depositing a layer of a polymer compositioncontaining at least one thermoplastic polymer and at least one epoxyresin modified by at least one aromatic polyamine on a support at theapplication temperature for said polymer composition, then depositing onthis layer a further layer of a polymer composition selected from thosedefined above at its application temperature. After depositing eachlayer it can be cured at about 200° C. to 250° C., for a period of about10 minutes to 12 hours. Curing can also be carried out after depositingall of the layers onto the coating. Preferably, curing is carried outafter depositing all of the layers, this implementation thus achievinggood cross linking of the layers between each other.

[0063] The present invention also concerns surface coatings comprisingat least one thermoplastic polymer preferably selected from the groupformed by polyetherimdes, polysulphones and polyphenylene ethers and atleast one epoxy resin modified by at least one aromatic polyaminecontaining at least two primary amine groups in its molecule, the epoxyresin being formed from at least one polyepoxide containing at least twoepoxy groups in its molecule and the molar ratio of the aromaticpolyamine to the epoxy resin being such that each amine groupcorresponds to 1.6 to 2.6 epoxy groups.

[0064] The invention also concerns multi-layer surface coatingscomprising at least two identical or different layers in which at leastone first layer contains at least one thermoplastic polymer preferablyselected from the group formed by polyetherimdes, polysulphones andpolyphenylene ethers and at least one epoxy resin modified by at leastone aromatic polyamine as defined above, and at least one second layerwhich is identical or different to said first layer, preferably selectedfrom the group formed by the reactive polymers described above and themodified polyolefins described above, or a mixture of these two producttypes. In the present description, in the case of coatings comprising atleast two layers, the term “first layer” does not imply that this layeris that which is in direct contact with the surface to be coated.

[0065] The following examples illustrate the invention without limitingits scope.

[0066] The polymer compositions in the following examples were preparedusing a twin screw extruder from CLEXTRAL; this extruder comprised aplurality of positions for introducing the reactants to be mixed. Forthese examples, the epoxy resin and aromatic polyamine were first mixed;this mixture will hereinafter be termed the “premix”. The thermoplasticpolymers were introduced via an inlet zone and the premix was introducedvia a further inlet zone. The rate for the premix was constant, and wasintroduced using a gear pump. In contrast, the thermoplastic polymerswere introduced using a gravimetric metering hopper which enabled therate of the thermoplastic polymers to be varied, and thus polymercompositions with different modified resin/thermoplastic polymer ratioscould be produced.

[0067] The thermoplastic polymers were introduced into the extruder'sinlet zone at the end opposite to the zone for recovering the polymercomposition. The temperature in this inlet zone was 100° C. They werethen entrained in a second zone where the temperature was 150° C. andinto which the premix was introduced. These reactants were thenentrained by the twin screw extruder, with the temperature inside theextruder slowly increasing to attain 185° C. and the extruder outlet.

EXAMPLE 1

[0068] In this example, mixtures of polymer compositions comprising apolyetherimide and a modified epoxy resin were prepared.

[0069] The modified epoxy resin comprised 8.016 kg of the diglycidylether of bis-phenol-A (DGEBA), sold under reference number LY556 byCIBA-GEIGY, and 3.984 kg of4,4′-methylene-bis(3-chloro-2,6-diethylaniline) (MCDEA), sold by LONZA.

[0070] Before its introduction into the extruder, this mixture washeated to 80° C. with stirring. The progress of the reaction of thismixture was measured by exclusion chromatography. The reactivity wasvery low: 5 hours at 60° C. resulted in a 1% advance in the reaction.

[0071] The polyetherimide used was sold by General Electric Plasticswith reference ULTEM 1000; its number average molecular mass was 26000g/mol and its granulometry was 300 micrometers. Before its introductioninto the extruder, the polyetherimide was kept in an oven at 120° C. fortwo hours.

[0072] The modified epoxy resin was introduced into the extruder at aconstant rate of 2 kg/h using a gear pump. The polyetherimide wasintroduced at a rate of 4.75 kg/h using a gravimetric metering hopper toobtain a composition containing 30% by weight of modified epoxy resin,then at a rate of 2.00 kg/h to produce a composition containing 50% byweight of modified epoxy resin, and finally at a rate of 1.30 kg/h toproduce a composition containing 60% by weight of modified epoxy resin,these percentages by weight of modified epoxy resin being calculatedwith respect to the total composition.

[0073] After extrusion, in order to carry out adhesion measurementsusing the lap shear test, these compositions were deposited on steel ata temperature corresponding to their application temperature—thesetemperatures are shown in Table 1a—, then cured at 220° C. for one hour.

[0074] These compositions were also pressed into a mould and cured at220° C. for one hour to form them into test pieces with a view todetermining their thermomechanical properties.

[0075] Measurements of steel adhesion, thermomechanical behaviour,resistance to sea water and ageing behaviour were carried out on thedifferent compositions with a view to using them as external pipelinecoatings.

[0076] The adhesion properties of the different compositions weredetermined using a lap shear method (ASTM D1002). To determine theadhesion, steel test pieces, previously cleaned with a stainless steelbrush rotating at high speed, were glued. The adhesive surface was(25.4×10⁻³)×(12.7×10⁻³) and the thickness of the adhesive joint was 125micrometers. Gluing was carried out by simple contact at a temperaturecorresponding to the application temperature for each composition, thenthey were cured for 1 hour at 220° C. These adhesion tests using the lapshear method were carried out using an apparatus sold by INSTRON(INSTRON-1175) provided with a measuring head of 100 kN (kiloNewton)with an operating speed of 10⁻³ m/min.

[0077] Examples 1.2, 1.3 and 1.4 of Table 1a are in accordance with theinvention; Example 1.1 is a comparative example; the composition ofExample 1.1 contained no modified epoxy resin; it contained only a ULTEM1000 polyetherimide. For the different compositions, the applicationtemperature was determined along with the maximum load. The lap shearbreaking stress was deduced by relating this maximum load to theadhesive surface area. TABLE 1a 1.2 1.3 1.4 1.1 (inven- (inven- (inven-Examples (comparative) tion) tion) tion) Modified epoxy resin (% 0 30 5060 by weight with respect to total composition) Application temperature320 230 210 200 (° C.) Maximum load 6.1 6.5 6.8 7.4 (kiloNewton) Stressat rupture (MPa) 19 20 21 23

[0078] This first series of results shows that the compositions of thepresent invention were applied at a temperature of less than 250° C. Thelap shear breaking stress for these compositions was very good: theywere all more or less 20 MPa.

[0079] The loss of adhesion after 6 months at 150° C. in air was low.The lap shear breaking stress measured for the composition containing30% of modified epoxy resin dropped from 20 MPa to 17 MPa.

[0080] The thermomechanical properties of the polymer compositions weredetermined using DMTA (Dynamic Mechanical Thermal Analysis), in sandwichmode. The measurements were carried out by moulding the differentcompositions into plates 2×10⁻³ thick at a pressure of 5 MPa, thenheating the mouldings to 220° C. for 1 hour. The elastic modulus and thetangent of the loss angle were measured as a function of temperature ata frequency of 1 Hz using a DMTA apparatus from Polymer Laboratories.

[0081] Glass transition temperatures (Tg) and the elastic modulus E′ at25° C., at 150° C. and at 175° C. were measured using the compositionsdefined in Table 1a. The results are shown in Table 1b. TABLE 1b 1.1(compar- 1.2 1.3 1.4 Examples ative) (invention) (invention) (invention)Tg, ° C. 220 218 215 215 Modulus E′ at 1600 1600 1000 1250 25° C., MPaModulus E′ at 1250 800 550 800 150° C., MPa Modulus E′ at 1200 600 350300 175° C., MPa

[0082] The elastic modulus indicates the stiffness of the materials.These results show that up to 150° C. the stiffness of the polymercompositions was comparable to that of polyetherimide (Example 1.1). At175° C., they still had sufficient stiffness for use as a coating.

[0083] A series of sea water resistance tests was also carried out. Thecompositions from Examples 1.1, 1.3 and 1.4 were moulded into (50×10⁻³m)×(50×10⁻³ m)×(2×10⁻³ m) plaques.

[0084] These test pieces were immersed in synthetic sea water containedin a sealed reactor heated to 160° C., at an absolute pressure of 0.62MPa. Water absorption measurements were carried out by determining thevariation in the weight of the test pieces after 3 months immersion. Theresults are shown in Table 1c. TABLE 1c Examples 1.1 (cormparative) 1.3(invention) 1.4 (invention) Water take-up (wt 4.4 3.6 3.2 %) Distortionlarge small none

[0085] The water take-up in the compositions of the invention was small.Increasing the quantity of epoxy resin reduced water take-up. Further,these compositions suffered little or no distortion. After 3 monthsimmersion, the test piece coatings were practically entirely unchanged.

EXAMPLE 2

[0086] In this example, mixtures of polymer compositions comprising apolyphenylene sulphone and a modified epoxy resin were prepared.

[0087] The modified epoxy resin comprised 8.016 kg of the diglycidylether of bis-phenol-A (DGEBA), .sold under reference number LY556 byCIBA-GEIGY, and 3.984 kg of MCDEA sold by LONZA. Before its introductioninto the extruder, this mixture was heated to 80° C. with stirring. Theprogress of the reaction of this mixture was measured by exclusionchromatography. The reactivity was very low: 5 hours at 60° C. resultedin a 1% advance in the reaction.

[0088] The polyphenylene sulphone used was RADEL R sold by AMOCO.

[0089] The modified epoxy resin was introduced into the extruder at aconstant rate of 2 kg/h using a gear pump. The polyphenylene sulphonewas introduced at a rate of 2.00 kg/h using a gravimetric meteringhopper to obtain a composition containing 50% by weight of modifiedepoxy resin, then at a rate of 1.10 kg/h to produce a compositioncontaining 65% by weight of modified epoxy resin. These percentages byweight of modified epoxy resin were calculated with respect to the totalcomposition.

[0090] After extrusion, in order to carry out adhesion measurementsusing the lap shear test, these compositions were deposited on steel ata temperature corresponding to their application temperature—thesetemperatures are shown in Table 2a—, then cured at 220° C. for one hour.To determine their thermomechanical properties, these compositions werepressed into a mould then cured at 220° C. for one hour to form theminto test pieces.

[0091] The adhesion properties of the different compositions weredetermined by means of a lap shear test (ASTM D1002) using the methoddescribed in Example 1.

[0092] Examples 2.2 and 2.3 of the following table are in accordancewith the invention; Example 2.1 is a comparative example the compositionof which contained no modified epoxy resin, but contained only a RADEL Rtype polyphenylene sulphone. For the different compositions, theapplication temperature was determined along with the maximum load. Thelap shear breaking stress was deduced by relating this maximum load tothe adhesive surface area. TABLE 2a 2.1 2.2 2.3 Examples (comparative)(invention) (invention) Modified epoxy resin (% 0 50 65 by weight withrespect to total composition) Application temperature 320 190 170 (° C.)Maximum load 6.5 6.1 6.8 (kiloNewton) Stress at rupture (MPa) 20 19 21

[0093] This first series of results shows that the compositions of thepresent invention were applied at a temperature of less than 200° C. Thelap shear breaking stress of these compositions was very good: they wereall more or less 19 MPa.

[0094] The thermomechanical properties of the polymer compositions weredetermined by DMTA in sandwich mode using the same process as in Example1.

[0095] Glass transition temperatures (Tg) and the elastic modulus E′ at25° C., 150° C. and at 175° C. were measured using the compositionsdefined in Table 2a. The results are shown in Table 2b. TABLE 2b 2.1 2.22.3 Examples (comparative) (invention) (invention) Tg, ° C. 220 205 200Modulus E′ at 25° C., 1200 1100 1300 MPa Modulus E′ at 150° C., 1050 850850 MPa Modulus E′ at 175° C., 1000 700 650 MPa

[0096] The elastic modulus indicates the stiffness of the materials.These results show that even when they were heated to quite a hightemperature, the stiffness of these polymer compositions was sufficientfor use as a coating.

[0097] A series of sea water resistance tests was also carried out. Thecompositions from Examples 2.1 and 2.2 were moulded into (50×10⁻³m)×(50×10⁻³ m)×(2×10⁻³ m) plaques. These test pieces were immersed insynthetic sea water contained in a sealed reactor heated to 160° C., atan absolute pressure of 0.62 MPa. Water absorption measurements werecarried out by determining the variation in the weight of the testpieces after 3 months immersion. TABLE 2c Examples 2.1 (comparative) 2.2(invention) Water take-up (wt %) 2.6 2 Distortion none none

[0098] The water take-up in the compositions of the invention was low.The increase in the quantity of epoxy resin reduced water take-up, andthis composition suffered little or no distortion. After 3 monthsimmersion, the test piece coating was unchanged.

EXAMPLE 3

[0099] In this example, a polymer composition comprising a polyphenyleneether and a modified epoxy resin was prepared.

[0100] The modified epoxy resin comprised 8.016 kg of the diglycidylether of bis-phenol-A (DGEBA), sold under reference number LY556 byCIBA-GEIGY, and 3.984 kg of MCDEA sold by LONZA.

[0101] Before its introduction into the extruder, this mixture washeated to 80° C. with stirring. The progress of the reaction of thismixture was measured by exclusion chromatography. The reactivity wasvery low: 5 hours at 60° C. resulted in a 1% advance in the reaction.

[0102] The polyphenylene ether used is sold by General Electric Plasticsunder reference PPE 800; its number average molecular mass is 12000g/mol.

[0103] The modified epoxy resin was introduced into the extruder at aconstant rate of 2 kg/h using a gear pump. The polyphenylene ether wasintroduced at a rate of 3.00 kg/h using a gravimetric metering hopper toobtain a composition containing 40% by weight of modified epoxy resin.The percentage by weight of modified epoxy resin was calculated withrespect to the total composition.

[0104] After extrusion, in order to carry out adhesion measurementsusing the lap shear test, this composition was deposited on steel at atemperature corresponding to its application temperature—thistemperature is shown in Table 3a—, then cured at 220° C. for one hour.

[0105] To determine its thermomechanical properties, this compositionwas pressed into a mould then cured at 220° C. for one hour to form atest piece.

[0106] The adhesion properties of the composition were determined usinga lap shear test (ASTM D 1002) using the method described in Example 1.

[0107] Example 3.2 of the following table was in accordance with theinvention. For Example 3.2, the application temperature was determinedalong with the maximum load. The lap shear breaking stress was deducedby relating this maximum load to the adhesive surface area.

[0108] Example 3.1 is a comparative example in which the compositioncontained no modified epoxy resin, but only contained a type PPE 800polyphenylene ether. However, the tests showed that when the applicationtemperature reached 300° C., the composition degraded: it oxidisedspontaneously on contact with the oxygen in the air and hardened.Further, this composition had no adhesive properties when applied attemperatures of less than 300° C. For this reason, the maximum loadcould not be determined for this composition. TABLE 3a 3.1 3.2 Examples(comparative) (invention) Modified epoxy resin (% 0 40 by weight withrespect to total composition) Application temperature 300 220 (° C.)Maximum load 0 3.9 (kiloNewton) Stress at rupture (MPa) 0 12

[0109] Composition 3.2 was applied at a temperature of 220° C. The lapshear breaking stress of these compositions was good: it was 12 MPa.

[0110] While composition 3.1 was difficult to apply at atmosphericpressure in ambient air, it was possible to produce the test piecesnecessary to determine the thermomechanical properties of thiscomposition.

[0111] The thermomechanical properties of the polymer compositions weredetermined by DMTA in sandwich mode using the same process as in Example1.

[0112] Glass transition temperatures (Tg) and the elastic modulus E′ at25° C., 150° C. and at 175° C. were measured using the compositionsdefined in Table 3a. The results are shown in Table 3b. TABLE 3b 3.1 3.2Examples (comparative) (invention) Tg, ° C. 210 205 Modulus E′ at 25°C., 1200 1400 MPa Modulus E′ at 150° C., 850 850 MPa Modulus E′ at 175°C., 750 650 MPa

[0113] The elastic modulus indicates the stiffness of the materials.These results show that even when they were heated to quite a hightemperature, the stiffness of the polymer composition of the inventionwas sufficient for use as a coating.

[0114] A series of sea water resistance tests was also carried out. Thecompositions from Examples 3.1 and 3.2 were moulded into (50×10⁻³m)×(50×10⁻³ m)×(2×10⁻³ m) plaques. These test pieces were immersed insynthetic sea water contained in a sealed reactor heated to 160° C., atan absolute pressure of 0.62 MPa. Water absorption measurements werecarried out by determining the variation in the weight of the testpieces after 3 months immersion. TABLE 3c Examples 3.1 (comparative) 3.2(invention) Water take-up (wt %) 0.5 1 Distortion none none

[0115] The water take-up in the compositions of the invention was low.This composition suffered no distortion. After 3 months immersion, thetest piece coating was unchanged.

EXAMPLE 4

[0116] In this example, mixtures of polymer compositions comprising apolyetherimide, a polyphenylene ether and a modified epoxy resin wereprepared.

[0117] The modified epoxy resin comprised 8.016 kg of the diglycidylether of bis-phenol-A (DGEBA), sold under reference number LY556 byCIBA-GEIGY, and 3.984 kg of MCDEA sold by LONZA.

[0118] Before its introduction into the extruder, this mixture washeated to 80° C. with stirring. The progress of the reaction of thismixture was measured by exclusion chromatography. The reactivity wasvery low: 5 hours at 60° C. resulted in a 1% advance in the reaction.

[0119] The polyetherimide used was sold by General Electric Plasticsunder the trade name ULTEM 1000. This polyetherimide was that used inExample 1 above. The polyphenylene ether used is sold by GeneralElectric Plastics under the trade name PPE 800; its number averagemolecular weight is 12000 g/mol. This polyphenylene ether was that usedin Example 3 of the present text.

[0120] The modified epoxy resin was introduced into the extruder at aconstant rate of 2 kg/h using a gear pump. The thermoplastic polymers(polyetherimide and polyphenylene ether) were introduced via the sameintroduction zone, the quantity of polyetherimide being equal to thequantity of polyphenylene ether. These two polymers were introduced at atotal rate of 2.00 kg/h using a gravimetric metering hopper, to obtain acomposition containing 50% by weight of modified epoxy resin, then at arate of I kg/h to produce a composition containing 67% by weight ofmodified epoxy resin. These percentages by weight of modified epoxyresin were calculated with respect to the total composition.

[0121] After extrusion, in order to carry out adhesion measurementsusing the lap shear test, these compositions were deposited on steel ata temperature corresponding to their application temperature—thesetemperatures are shown in Table 4a—, then cured at 220° C. for one hour.

[0122] To determine their thermomechanical properties, thesecompositions were pressed into a mould then cured at 220° C. for onehour to form them into test pieces.

[0123] The adhesion properties of the different compositions weredetermined using the ASTM D1002 method as described in Example 1.

[0124] Examples 4.2 and 4.3 of the following table are in accordancewith the invention; Example 4.1 is a comparative example the compositionof which contained no modified epoxy resin, but contained 50% by weightof PPE 800 type polyphenylene ether and 50% by weight of ULTEM 1000 typepolyetherimide. For the different compositions, the applicationtemperature was determined along with the maximum load. The lap shearbreaking stress was deduced by relating this maximum load to theadhesive surface area. TABLE 4a 4.1 4.2 4.3 Examples (comparative)(invention) (invention) Modified epoxy resin (% 0 50 67 by weight withrespect to total composition) Application temperature 300 220 160 (° C.)Maximum load 2.2 7.4 7.7 (kiloNewton) Stress at rupture (MPa) 7 23 24

[0125] This first series of results shows that the compositions of thepresent invention were applied at a temperature of less than 250° C. Thelap shear breaking, stress of these compositions was very good: theywere all more or less equal to 23 MPa.

[0126] The thermomechanical properties of the polymer compositions weredetermined by DMTA in sandwich mode using the same process as in Example1.

[0127] Glass transition temperatures (Tg) and the elastic modulus E′ at25° C., 150° C. and at 175° C. were measured using the compositionsdefined in Table 4a. The results are shown in Table 4b. TABLE 4b 4.1 4.24.3 Examples (comparative) (invention) (invention) Tg, ° C. 220 215 210Modulus E’ at 25° C., 1100 1100 1100 MPa Modulus E’ at 150° C., 1050 900700 MPa Modulus E’ at 175° C., 900 600 200 MPa

[0128] The elastic modulus indicates the stiffness of the materials.These results show that even when they were heated to quite a hightemperature, the stiffness of these polymer compositions was sufficientfor use as a coating.

EXAMPLE 5

[0129] A series of breaking stress tests were carried out on multi-layercompositions. A first layer of a composition containing a thermoplasticpolymer and a modified epoxy resin was directly deposited onto a typeXC12 carbon steel test piece; then a layer of graft polyethylene wasdeposited on the first layer. The graft polyethylene used in thefollowing examples contained 99% of FINATHENE 3802® sold by FINA and 1%of an equimolar mixture of 4-maleimidobenzoic acid and ARALDITE GT7071™, sold by CIBA-GEIGY. The first layer—100 micrometers thick—wasapplied by heating this first layer to its application temperature andmaintaining that temperature for a period of a few minutes to about anhour—in the following tables, this variable is termed the “first layercure time”. The second layer—300 micrometers thick—was then deposited at220° C., then this latter temperature was maintained for one hour. Inthe case described in Examples 5b and 5d, the test piece was firstcoated with an adhesion primer, then the two layers described above weredeposited in succession.

EXAMPLE 5b

[0130] In this example, the first layer deposited directly on the testpiece was formed from a mixture comprising a polyetherimide and amodified epoxy resin. The reactants and the operating method used werethose described in Example 1 of the present description, but the curetime for the first layer was varied. The polyetherimide represented 60%by weight of the mixture and the modified epoxy resin represented 40% byweight of the mixture. TABLE 5a Examples 5a.1 5a.2 5a.3 First layer cure10 30 60 time (minutes) Maximum load 3.8 3.7 1.1 (kiloNewton) Breakingstress 12 12 3.5 (MPa)

[0131] It can be seen from these results that if good adhesion betweenthe layers is to be obtained, the polymer layers must not be polymerisedto too great an extent.

EXAMPLE 5b

[0132] This example used the same procedure as that for Example 5a, thefirst layer cure time being 10 minutes. The only difference was that thesteel onto which the layers were coated was first treated with a thinlayer—50 micrometers thick—of an epoxy primer formed from 2 moles ofDGEBA to 1 mole of MCDEA, then pre-polymerised at 150° C., and thelayers described above in Example 5a were deposited onto this primer.The tension test established a breaking stress of 12 MPa.

EXAMPLE 5c

[0133] In this example, the first layer deposited directly on the testpiece was formed from a mixture comprising a RADEL A type polyethersulphone and a modified epoxy resin. The reactants to produce themodified epoxy resin and the operating method used were those describedin Example 2 of the present description. The polyether sulphonerepresented 60% by weight of the mixture and the modified epoxy resinrepresented 40% by weight of the mixture. TABLE 5c Example 5c.1 5c.25c.3 First layer cure 10 30 60 time (minutes) Maximum load 3.7 3.2 1.6(kiloNewton) Breaking stress 11.6 10 5 (MPa)

EXAMPLE 5d

[0134] This example was carried out using the same procedure as that forExample 5c, the first layer cure time being 10 minutes. The onlydifference was that the steel onto which the layers were coated wasfirst treated with a thin layer (50 micrometers thick) of an epoxyprimer formed from 2 moles of DGEBA to 1 mole of MCDEA, thenpre-polymerised at 150° C., and the layers described above in Example 5cwere deposited onto this primer. The tension test established a breakingstress of 12 MPa.

[0135] The tension tests carried out on the coated steel test piecesdescribed in Examples 5a to 5d show that the break was cohesive innature, i.e., it did not occur between the layers but in the graftpolyethylene layer. This demonstrates the good cohesion of thecomposition containing a thermoplastic polymer and a modified epoxyresin to steel, and the good cohesion of the layers between themselves.These tests were carried out using the method described in Example 1.

[0136] The preceding examples can be repeated with similar success bysubstituting the generically or specifically described reactants and/oroperating conditions of this invention for those used in the precedingexamples. Also, the preceding specific embodiments are to be construedas merely illustrative, and not limitative of the remainder of thedisclosure in any way whatsoever.

[0137] The entire disclosure of all applications, patents andpublications, cited above and below, and of corresponding Frenchapplication 98/00758 and Provisional Application No. 60/084,669 filedMay 7, 1998, are hereby incorporated by reference.

[0138] From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention, and withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

1. A substrate coated with a polymer composition comprising at least onethermoplastic polymer selected from the group consisting ofpolyetherimides, polysulphones and polyphenylene ethers and at least oneepoxy resin modified by at least one aromatic polyamine containing atleast two primary amine groups in its molecule, the epoxy resin beingformed from at least one polyepoxide containing at least two epoxygroups in its molecule and the epoxy resin having a molar ratio of thearomatic polyamine to the epoxy being such that each amine groupcorresponds to 1.6 to 2.6 epoxy groups; wherein said polymer compositionis preparable from at least one thermoplastic polymer and at least oneepoxy resin modified by at least one aromatic polyamine, without asolvent, in a molten state at a temperature of about 100° C. to 250° C.2. A substrate according to claim 1, wherein the substrate comprises ametal or a metallic composition.
 3. A substrate according to claim 1,wherein said at least one thermoplastic polymer is present in an amountof 30% to 70% by weight with respect to the total polymer compositionweight.